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Adambukulam C, Johnson BC, Morello A, Laucht A. Hyperfine Spectroscopy and Fast, All-Optical Arbitrary State Initialization and Readout of a Single, Ten-Level ^{73}Ge Vacancy Nuclear Spin Qudit in Diamond. Phys Rev Lett 2024; 132:060603. [PMID: 38394595 DOI: 10.1103/physrevlett.132.060603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 01/11/2024] [Indexed: 02/25/2024]
Abstract
A high-spin nucleus coupled to a color center can act as a long-lived memory qudit in a spin-photon interface. The germanium vacancy (GeV) in diamond has attracted recent attention due to its excellent spectral properties and provides access to the ten-dimensional Hilbert space of the I=9/2 ^{73}Ge nucleus. Here, we observe the ^{73}GeV hyperfine structure, perform nuclear spin readout, and optically initialize the ^{73}Ge spin into any eigenstate on a μs timescale and with a fidelity of up to ∼84%. Our results establish ^{73}GeV as an optically addressable high-spin quantum platform for a high-efficiency spin-photon interface as well as for foundational quantum physics and metrology.
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Affiliation(s)
- C Adambukulam
- School of Electrical Engineering and Telecommunications, University of New South Wales, Kensington, NSW 2052, Australia
| | - B C Johnson
- School of Science, RMIT University, Melbourne, VIC 3001, Australia
| | - A Morello
- School of Electrical Engineering and Telecommunications, University of New South Wales, Kensington, NSW 2052, Australia
| | - A Laucht
- School of Electrical Engineering and Telecommunications, University of New South Wales, Kensington, NSW 2052, Australia
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2
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Adambukulam C, Sewani VK, Stemp HG, Asaad S, Mądzik MT, Morello A, Laucht A. An ultra-stable 1.5 T permanent magnet assembly for qubit experiments at cryogenic temperatures. Rev Sci Instrum 2021; 92:085106. [PMID: 34470423 DOI: 10.1063/5.0055318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/14/2021] [Indexed: 06/13/2023]
Abstract
Magnetic fields are a standard tool in the toolbox of every physicist and are required for the characterization of materials, as well as the polarization of spins in nuclear magnetic resonance or electron paramagnetic resonance experiments. Quite often, a static magnetic field of sufficiently large, but fixed, magnitude is suitable for these tasks. Here, we present a permanent magnet assembly that can achieve magnetic field strengths of up to 1.5 T over an air gap length of 7 mm. The assembly is based on a Halbach array of neodymium magnets, with the inclusion of the soft magnetic material Supermendur to boost the magnetic field strength inside the air gap. We present the design, simulation, and characterization of the permanent magnet assembly, measuring an outstanding magnetic field stability with a drift rate of |D| < 2.8 ppb/h. Our measurements demonstrate that this assembly can be used for spin qubit experiments inside a dilution refrigerator, successfully replacing the more expensive and bulky superconducting solenoids.
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Affiliation(s)
- C Adambukulam
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Sydney, New South Wales 2052, Australia
| | - V K Sewani
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Sydney, New South Wales 2052, Australia
| | - H G Stemp
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Sydney, New South Wales 2052, Australia
| | - S Asaad
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Sydney, New South Wales 2052, Australia
| | - M T Mądzik
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Sydney, New South Wales 2052, Australia
| | - A Morello
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Sydney, New South Wales 2052, Australia
| | - A Laucht
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Sydney, New South Wales 2052, Australia
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3
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Yoneda J, Huang W, Feng M, Yang CH, Chan KW, Tanttu T, Gilbert W, Leon RCC, Hudson FE, Itoh KM, Morello A, Bartlett SD, Laucht A, Saraiva A, Dzurak AS. Coherent spin qubit transport in silicon. Nat Commun 2021; 12:4114. [PMID: 34226564 PMCID: PMC8257656 DOI: 10.1038/s41467-021-24371-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 05/23/2021] [Indexed: 11/09/2022] Open
Abstract
A fault-tolerant quantum processor may be configured using stationary qubits interacting only with their nearest neighbours, but at the cost of significant overheads in physical qubits per logical qubit. Such overheads could be reduced by coherently transporting qubits across the chip, allowing connectivity beyond immediate neighbours. Here we demonstrate high-fidelity coherent transport of an electron spin qubit between quantum dots in isotopically-enriched silicon. We observe qubit precession in the inter-site tunnelling regime and assess the impact of qubit transport using Ramsey interferometry and quantum state tomography techniques. We report a polarization transfer fidelity of 99.97% and an average coherent transfer fidelity of 99.4%. Our results provide key elements for high-fidelity, on-chip quantum information distribution, as long envisaged, reinforcing the scaling prospects of silicon-based spin qubits.
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Affiliation(s)
- J Yoneda
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia. .,Tokyo Tech Academy for Super Smart Society, Tokyo Institute of Technology, Tokyo, Japan.
| | - W Huang
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia.,Solid State Physics Laboratory, ETH Zurich, Zurich, Switzerland
| | - M Feng
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - C H Yang
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - K W Chan
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - T Tanttu
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - W Gilbert
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - R C C Leon
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - F E Hudson
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - K M Itoh
- School of Fundamental Science and Technology, Keio University, Yokohama, Japan
| | - A Morello
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - S D Bartlett
- Centre for Engineered Quantum Systems, School of Physics, University of Sydney, Sydney, NSW, Australia
| | - A Laucht
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - A Saraiva
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia
| | - A S Dzurak
- School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia.
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4
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Leon RCC, Yang CH, Hwang JCC, Lemyre JC, Tanttu T, Huang W, Chan KW, Tan KY, Hudson FE, Itoh KM, Morello A, Laucht A, Pioro-Ladrière M, Saraiva A, Dzurak AS. Coherent spin control of s-, p-, d- and f-electrons in a silicon quantum dot. Nat Commun 2020; 11:797. [PMID: 32047151 PMCID: PMC7012832 DOI: 10.1038/s41467-019-14053-w] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 12/11/2019] [Indexed: 11/09/2022] Open
Abstract
Once the periodic properties of elements were unveiled, chemical behaviour could be understood in terms of the valence of atoms. Ideally, this rationale would extend to quantum dots, and quantum computation could be performed by merely controlling the outer-shell electrons of dot-based qubits. Imperfections in semiconductor materials disrupt this analogy, so real devices seldom display a systematic many-electron arrangement. We demonstrate here an electrostatically confined quantum dot that reveals a well defined shell structure. We observe four shells (31 electrons) with multiplicities given by spin and valley degrees of freedom. Various fillings containing a single valence electron-namely 1, 5, 13 and 25 electrons-are found to be potential qubits. An integrated micromagnet allows us to perform electrically-driven spin resonance (EDSR), leading to faster Rabi rotations and higher fidelity single qubit gates at higher shell states. We investigate the impact of orbital excitations on single qubits as a function of the dot deformation and exploit it for faster qubit control.
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Affiliation(s)
- R C C Leon
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia.
| | - C H Yang
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - J C C Hwang
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
- Research and Prototype Foundry, The University of Sydney, Sydney, NSW, 2006, Australia
| | - J Camirand Lemyre
- Institut Quantique et Département de Physique, Université de Sherbrooke, Sherbrooke, Québec, J1K 2R1, Canada
| | - T Tanttu
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - W Huang
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - K W Chan
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - K Y Tan
- QCD Labs COMP Centre of Excellence, Department of Applied Physics, Aalto University, 00076, Aalto, Finland
| | - F E Hudson
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - K M Itoh
- School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohokuku, Yokohama, 223-8522, Japan
| | - A Morello
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - A Laucht
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - M Pioro-Ladrière
- Institut Quantique et Département de Physique, Université de Sherbrooke, Sherbrooke, Québec, J1K 2R1, Canada
- Quantum Information Science Program, Canadian Institute for Advanced Research, Toronto, ON, M5G 1Z8, Canada
| | - A Saraiva
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia.
| | - A S Dzurak
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, 2052, Australia.
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5
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Zhao R, Tanttu T, Tan KY, Hensen B, Chan KW, Hwang JCC, Leon RCC, Yang CH, Gilbert W, Hudson FE, Itoh KM, Kiselev AA, Ladd TD, Morello A, Laucht A, Dzurak AS. Single-spin qubits in isotopically enriched silicon at low magnetic field. Nat Commun 2019; 10:5500. [PMID: 31796728 PMCID: PMC6890755 DOI: 10.1038/s41467-019-13416-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 11/06/2019] [Indexed: 11/09/2022] Open
Abstract
Single-electron spin qubits employ magnetic fields on the order of 1 Tesla or above to enable quantum state readout via spin-dependent-tunnelling. This requires demanding microwave engineering for coherent spin resonance control, which limits the prospects for large scale multi-qubit systems. Alternatively, singlet-triplet readout enables high-fidelity spin-state measurements in much lower magnetic fields, without the need for reservoirs. Here, we demonstrate low-field operation of metal-oxide-silicon quantum dot qubits by combining coherent single-spin control with high-fidelity, single-shot, Pauli-spin-blockade-based ST readout. We discover that the qubits decohere faster at low magnetic fields with [Formula: see text] μs and [Formula: see text] μs at 150 mT. Their coherence is limited by spin flips of residual 29Si nuclei in the isotopically enriched 28Si host material, which occur more frequently at lower fields. Our finding indicates that new trade-offs will be required to ensure the frequency stabilization of spin qubits, and highlights the importance of isotopic enrichment of device substrates for the realization of a scalable silicon-based quantum processor.
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Affiliation(s)
- R Zhao
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia.
- National Institute of Standards and Technology, 325 Broadway, Boulder, CO, 80305, USA.
| | - T Tanttu
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
| | - K Y Tan
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, 00076, Aalto, Finland
- IQM Finland Oy, Vaisalantie 6 C, 02130, Espoo, Finland
| | - B Hensen
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
| | - K W Chan
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
| | - J C C Hwang
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
- Research and Prototype Foundry, The University of Sydney, Sydney, NSW, 2006, Australia
| | - R C C Leon
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
| | - C H Yang
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
| | - W Gilbert
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
| | - F E Hudson
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
| | - K M Itoh
- School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
| | - A A Kiselev
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, CA, 90265, USA
| | - T D Ladd
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, CA, 90265, USA
| | - A Morello
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
| | - A Laucht
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
| | - A S Dzurak
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia.
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6
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Minehart J, Eguchi T, Morello A, Adusumilli P. OA14.03 Clinical Rationale and Preclinical Evidence for Chimeric Antigen Receptor (CAR) T Cell Therapy Clinical Trial in KRAS-Mutant Lung Cancer. J Thorac Oncol 2019. [DOI: 10.1016/j.jtho.2019.08.485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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7
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Monsellato I, Morello A, Argenio G, Canepa MC, Lenti LM, Priora F. Spontaneous bladder rupture mimicking a jejuno-ileal perforation. G Chir 2018; 34:315-318. [PMID: 30444481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Spontaneous urinary bladder perforation is a very rare disease. The main cause of urinary perforation, indeed, is a damage to the urinary bladder wall by blunt or penetrating trauma. There are only few idiopathic spontaneous rupture of urinary bladder (ISRUB) cases reported in the literature. Pre-operative diagnosis is very difficult due to similar symptoms, laboratory and imaging findings of a gastrointestinal perforation that is usually excluded intraoperatively. Herein we report a case of a 91-year-old man presented to the emergency department with a spontaneous bladder perforation mimicking an ileal perforation.
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8
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Lamberti M, Gagliano A, Italiano D, Morello A, Guerriero L, D’Amico G, Germanò E, Calabrò M, Persico A, Spina E. EKG Parameters in Children and Adolescents Treated with Second-Generation Antipsychotics: A 24-Months Prospective Follow-Up Study. Clin Ther 2017. [DOI: 10.1016/j.clinthera.2017.05.135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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9
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Laucht A, Kalra R, Simmons S, Dehollain JP, Muhonen JT, Mohiyaddin FA, Freer S, Hudson FE, Itoh KM, Jamieson DN, McCallum JC, Dzurak AS, Morello A. A dressed spin qubit in silicon. Nat Nanotechnol 2017; 12:61-66. [PMID: 27749833 DOI: 10.1038/nnano.2016.178] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 08/17/2016] [Indexed: 06/06/2023]
Abstract
Coherent dressing of a quantum two-level system provides access to a new quantum system with improved properties-a different and easily tunable level splitting, faster control and longer coherence times. In our work we investigate the properties of the dressed, donor-bound electron spin in silicon, and assess its potential as a quantum bit in scalable architectures. The two dressed spin-polariton levels constitute a quantum bit that can be coherently driven with an oscillating magnetic field, an oscillating electric field, frequency modulation of the driving field or a simple detuning pulse. We measure coherence times of and , one order of magnitude longer than those of the undressed spin. Furthermore, the use of the dressed states enables coherent coupling of the solid-state spins to electric fields and mechanical oscillations.
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Affiliation(s)
- Arne Laucht
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Rachpon Kalra
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Stephanie Simmons
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Juan P Dehollain
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Juha T Muhonen
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Fahd A Mohiyaddin
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Solomon Freer
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Fay E Hudson
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Kohei M Itoh
- School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kanagawa 223-8522, Japan
| | - David N Jamieson
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Jeffrey C McCallum
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Andrew S Dzurak
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - A Morello
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
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10
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van Donkelaar J, Yang C, Alves ADC, McCallum JC, Hougaard C, Johnson BC, Hudson FE, Dzurak AS, Morello A, Spemann D, Jamieson DN. Single atom devices by ion implantation. J Phys Condens Matter 2015; 27:154204. [PMID: 25783169 DOI: 10.1088/0953-8984/27/15/154204] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
To expand the capabilities of semiconductor devices for new functions exploiting the quantum states of single donors or other impurity atoms requires a deterministic fabrication method. Ion implantation is a standard tool of the semiconductor industry and we have developed pathways to deterministic ion implantation to address this challenge. Although ion straggling limits the precision with which atoms can be positioned, for single atom devices it is possible to use post-implantation techniques to locate favourably placed atoms in devices for control and readout. However, large-scale devices will require improved precision. We examine here how the method of ion beam induced charge, already demonstrated for the deterministic ion implantation of 14 keV P donor atoms in silicon, can be used to implant a non-Poisson distribution of ions in silicon. Further, we demonstrate the method can be developed to higher precision by the incorporation of new deterministic ion implantation strategies that employ on-chip detectors with internal charge gain. In a silicon device we show a pulse height spectrum for 14 keV P ion impact that shows an internal gain of 3 that has the potential of allowing deterministic implantation of sub-14 keV P ions with reduced straggling.
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Affiliation(s)
- Jessica van Donkelaar
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia
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11
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Muhonen JT, Laucht A, Simmons S, Dehollain JP, Kalra R, Hudson FE, Freer S, Itoh KM, Jamieson DN, McCallum JC, Dzurak AS, Morello A. Quantifying the quantum gate fidelity of single-atom spin qubits in silicon by randomized benchmarking. J Phys Condens Matter 2015; 27:154205. [PMID: 25783435 DOI: 10.1088/0953-8984/27/15/154205] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Building upon the demonstration of coherent control and single-shot readout of the electron and nuclear spins of individual (31)P atoms in silicon, we present here a systematic experimental estimate of quantum gate fidelities using randomized benchmarking of 1-qubit gates in the Clifford group. We apply this analysis to the electron and the ionized (31)P nucleus of a single P donor in isotopically purified (28)Si. We find average gate fidelities of 99.95% for the electron and 99.99% for the nuclear spin. These values are above certain error correction thresholds and demonstrate the potential of donor-based quantum computing in silicon. By studying the influence of the shape and power of the control pulses, we find evidence that the present limitation to the gate fidelity is mostly related to the external hardware and not the intrinsic behaviour of the qubit.
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Affiliation(s)
- J T Muhonen
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, NSW 2052, Australia
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12
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Veldhorst M, Hwang JCC, Yang CH, Leenstra AW, de Ronde B, Dehollain JP, Muhonen JT, Hudson FE, Itoh KM, Morello A, Dzurak AS. An addressable quantum dot qubit with fault-tolerant control-fidelity. Nat Nanotechnol 2014; 9:981-985. [PMID: 25305743 DOI: 10.1038/nnano.2014.216] [Citation(s) in RCA: 199] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 08/28/2014] [Indexed: 06/04/2023]
Abstract
Exciting progress towards spin-based quantum computing has recently been made with qubits realized using nitrogen-vacancy centres in diamond and phosphorus atoms in silicon. For example, long coherence times were made possible by the presence of spin-free isotopes of carbon and silicon. However, despite promising single-atom nanotechnologies, there remain substantial challenges in coupling such qubits and addressing them individually. Conversely, lithographically defined quantum dots have an exchange coupling that can be precisely engineered, but strong coupling to noise has severely limited their dephasing times and control fidelities. Here, we combine the best aspects of both spin qubit schemes and demonstrate a gate-addressable quantum dot qubit in isotopically engineered silicon with a control fidelity of 99.6%, obtained via Clifford-based randomized benchmarking and consistent with that required for fault-tolerant quantum computing. This qubit has dephasing time T2* = 120 μs and coherence time T2 = 28 ms, both orders of magnitude larger than in other types of semiconductor qubit. By gate-voltage-tuning the electron g*-factor we can Stark shift the electron spin resonance frequency by more than 3,000 times the 2.4 kHz electron spin resonance linewidth, providing a direct route to large-scale arrays of addressable high-fidelity qubits that are compatible with existing manufacturing technologies.
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Affiliation(s)
- M Veldhorst
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - J C C Hwang
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - C H Yang
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - A W Leenstra
- University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - B de Ronde
- University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - J P Dehollain
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - J T Muhonen
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - F E Hudson
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - K M Itoh
- School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - A Morello
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - A S Dzurak
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
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13
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Morello A, Millán A, de Jongh LJ. Observation of zero-point quantum fluctuations of a single-molecule magnet through the relaxation of its nuclear spin bath. Phys Rev Lett 2014; 112:117202. [PMID: 24702408 DOI: 10.1103/physrevlett.112.117202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Indexed: 06/03/2023]
Abstract
A single-molecule magnet placed in a magnetic field perpendicular to its anisotropy axis can be truncated to an effective two-level system, with easily tunable energy splitting. The quantum coherence of the molecular spin is largely determined by the dynamics of the surrounding nuclear spin bath. Here we report the measurement of the nuclear spin-lattice relaxation rate 1/T1n in a single crystal of the single-molecule magnet Mn12-ac, at T ≈ 30 mK in perpendicular fields B⊥ up to 9 T. The relaxation channel at B ≈ 0 is dominated by incoherent quantum tunneling of the Mn12-ac spin S, aided by the nuclear bath itself. However for B⊥>5 T we observe an increase of 1/T1n by several orders of magnitude up to the highest field, despite the fact that the molecular spin is in its quantum mechanical ground state. This striking observation is a consequence of the zero-point quantum fluctuations of S, which allow it to mediate the transfer of energy from the excited nuclear spin bath to the crystal lattice at much higher rates. Our experiment highlights the importance of quantum fluctuations in the interaction between an "effective two-level system" and its surrounding spin bath.
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Affiliation(s)
- A Morello
- Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden, The Netherlands and Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - A Millán
- Instituto de Ciencia de Materiales de Aragón, C.S.I.C. Universidad de Zaragoza, 50009 Zaragoza, Spain
| | - L J de Jongh
- Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden, The Netherlands
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14
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Büch H, Mahapatra S, Rahman R, Morello A, Simmons MY. Spin readout and addressability of phosphorus-donor clusters in silicon. Nat Commun 2013; 4:2017. [DOI: 10.1038/ncomms3017] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Accepted: 05/16/2013] [Indexed: 11/09/2022] Open
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15
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Abstract
The intense interest in spin-based quantum information processing has caused an increasing overlap between the two traditionally distinct disciplines of magnetic resonance and nanotechnology. In this work we discuss rigorous design guidelines to integrate microwave circuits with charge-sensitive nanostructures, and describe how to simulate such structures accurately and efficiently. We present a new design for an on-chip, broadband, nanoscale microwave line that optimizes the magnetic field used to drive a spin-based quantum bit (or qubit) while minimizing the disturbance to a nearby charge sensor. This new structure was successfully employed in a single-spin qubit experiment, and shows that the simulations accurately predict the magnetic field values even at frequencies as high as 30 GHz.
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Affiliation(s)
- J P Dehollain
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney NSW 2052, Australia.
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16
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Duaso J, Rojo G, Cabrera G, Galanti N, Bosco C, Maya J, Morello A, Kemmerling U. Trypanosoma cruzi induces tissue disorganization and destruction of chorionic villi in an ex vivo infection model of human placenta. Placenta 2010; 31:705-11. [DOI: 10.1016/j.placenta.2010.05.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 05/03/2010] [Accepted: 05/04/2010] [Indexed: 11/27/2022]
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17
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Abstract
We present a systematic review of features due to resonant electron tunnelling, observable in transport spectroscopy experiments on quantum dots and single donors. The review covers features attributable to intrinsic properties of the dot (orbital, spin and valley states) as well as extrinsic effects (phonon/photon emission/absorption, features in the charge reservoirs, coupling to nearby charge centres). We focus on the most common operating conditions, neglecting effects due to strong coupling to the leads. By discussing the experimental signatures of each type of feature, we aim at providing practical methods to distinguish between their different physical origins. The correct classification of the resonant tunnelling features is an essential requirement to understand the details of the confining potential or to predict the performance of the dot for quantum information processing.
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Affiliation(s)
- C C Escott
- Australian Research Council Centre of Excellence for Quantum Computer Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW 2052, Australia
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18
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Minutolo V, Gagliano G, Angirillo G, Minutolo O, Morello A, Rinzivillo C. Intestinal obstruction due to idiopathic sclerosing encapsulating peritonitis. Clinical report and review of literature. G Chir 2008; 29:173-176. [PMID: 18419984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The sclerosing peritonitis (SP) is a rare illness secondary to the peritoneal dialysis or due to intraperitoneal chemotherapy or the positioning of a peritoneal-jugular shunt in cirrhotic patient with refractory ascites or due to unknown other factors (idiopathic form) like in our patient. The clinical pattern is various and insidious, but when an intestinal occlusive symptomatology is presents an urgent operation is mandatory. The surgical operation is often not easy and asks for a lot of attention especially in the dialyzed subject or in patients with cirrhosis, due to the possibility of postoperative bleeding and other serious complications that can result in fatal outcome. In this report we describe surgical treatment, pathologic pattern and clinical findings of this rare disease.
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Affiliation(s)
- V Minutolo
- Dipartimento Scienze Chirurgiche, Trapianti d'Organo, Università degli Studi di Catania
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19
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Gambino D, Otero L, Maya J, Morello A, Rigol C, Barriga G, Rodriguez J, Folch C, Norambuena E, Gonzalez M, Azar C, Cerecetto H. Insight into the Bioreductive Mode of Action of Antitrypanosomal 5- Nitrofuryl Containing Thiosemicarbazones. Med Chem 2008; 4:11-7. [DOI: 10.2174/157340608783331470] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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20
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Salman Z, Chow KH, Miller RI, Morello A, Parolin TJ, Hossain MD, Keeler TA, Levy CDP, MacFarlane WA, Morris GD, Saadaoui H, Wang D, Sessoli R, Condorelli GG, Kiefl RF. Local magnetic properties of a monolayer of Mn12 single molecule magnets. Nano Lett 2007; 7:1551-5. [PMID: 17488049 DOI: 10.1021/nl070366a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The magnetic properties of a monolayer of Mn12 single molecule magnets grafted onto a silicon (Si) substrate have been investigated using depth-controlled beta-detected nuclear magnetic resonance. A low-energy beam of spin-polarized radioactive 8Li was used to probe the local static magnetic field distribution near the Mn12 monolayer in the Si substrate. The resonance line width varies strongly as a function of implantation depth as a result of the magnetic dipolar fields generated by the Mn12 electronic magnetic moments. The temperature dependence of the line width indicates that the magnetic properties of the Mn12 moments in this low-dimensional configuration differ from bulk Mn12.
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Affiliation(s)
- Z Salman
- Clarendon Laboratory, Department of Physics, Oxford University, Parks Road, Oxford OX1 3PU, UK.
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Abstract
The high prevalence of habitual snoring (35% of the general population) and the increasing demand for an effective treatment have led, in the last decade, to the generalisation of laser-assisted uvulopalatoplasty (LAUP). However, acceptable studies on its effectiveness are lacking. The present randomised, placebo-controlled study included 25 nonapnoeic and mild obstructive sleep apnoea snorers to evaluate LAUP effectiveness for snoring. Group I received a one-stage LAUP treatment and group II a placebo (simulated snore surgery followed by an oral placebo). Before each treatment and 3 months after, the variables and procedures assessed were: body weight; sleepiness (Epworth sleepiness scale); quality of life (SF-36); subjective snoring intensity (0-10 analogue scale); objective snoring intensity (average decibel intensity); snoring index (number of snores per hour); and apnoea/hypopnea index. No differences were observed in body weight, sleepiness, quality of life, subjective and objective intensity, and frequency of snoring, and apnoea/hypopnea index between the groups before and 3 months after treatment. In conclusion, this study provides evidence of the lack of effectiveness of one-stage laser-assisted uvulopalatoplasty for snoring in nonapnoeic and mild obstructive sleep apnoea patients, with the result that it does not meet the expectations generated by the procedure.
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Affiliation(s)
- F Larrosa
- Otorhinolaryngology Service, Institut d'Investigacions Biomediques August Pi Sunyer, University of Barcelona, Barcelona, Spain
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Morello A, Bakharev ON, Brom HB, Sessoli R, de Jongh LJ. Nuclear spin dynamics in the quantum regime of a single-molecule magnet. Phys Rev Lett 2004; 93:197202. [PMID: 15600873 DOI: 10.1103/physrevlett.93.197202] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2003] [Indexed: 05/24/2023]
Abstract
We show that the nuclear spin dynamics in the single-molecule magnet Mn12-ac below 1 K is governed by quantum tunneling fluctuations of the cluster spins, combined with intercluster nuclear spin diffusion. We also obtain the first experimental proof that-surprisingly-even deep in the quantum regime the nuclear spins remain in good thermal contact with the lattice phonons. We propose a simple model for how T-independent tunneling fluctuations can relax the nuclear polarization to the lattice that may serve as a framework for more sophisticated theories.
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Affiliation(s)
- A Morello
- Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden, The Netherlands.
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Rinzivillo C, Minutolo V, Gagliano G, Minutolo G, Morello A, Scilletta B, Li Destri G. Splenic trauma following colonoscopy. G Chir 2003; 24:309-11. [PMID: 14664189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
A case of splenic trauma after colonoscopy is reported. After description of their experience, the Authors report a review of the literature and some considerations about clinical diagnosis and surgical or medical therapy for this pathology.
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Morello A, Mettes FL, Luis F, Fernández JF, Krzystek J, Aromí G, Christou G, de Jongh LJ. Long-range ferromagnetic dipolar ordering of high-spin molecular clusters. Phys Rev Lett 2003; 90:017206. [PMID: 12570647 DOI: 10.1103/physrevlett.90.017206] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2002] [Indexed: 05/24/2023]
Abstract
We report the first example of a transition to long-range magnetic order in a purely dipolarly interacting molecular magnet. For the magnetic cluster compound Mn6O4Br4(Et2dbm)6, the anisotropy experienced by the total spin S = 12 of each cluster is so small that spin-lattice relaxation remains fast down to the lowest temperatures, thus enabling dipolar order to occur within experimental times at T(c) = 0.16 K. In high magnetic fields, the relaxation rate becomes drastically reduced and the interplay between nuclear- and electron-spin lattice relaxation is revealed.
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Affiliation(s)
- A Morello
- Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
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25
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Morello A, Porcaro S, Lima J, Impallaria P. Endocrine disorder as the only sign of chronic "non-hypertensive" hydrocephalus. J Neurosurg Sci 2002; 46:81-4. [PMID: 12232554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
Three cases of "non-hypertensive" chronic hydrocephalus, 2 of which associated with early puberty and 1 with primary amenorrhea, are reported. Hormonal secretion deficiencies were confirmed by laboratory investigations. Only 1 of the 3 patients was surgically treated with a shunting device.
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Affiliation(s)
- A Morello
- University of Palermo, Palermo, Italy
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26
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Maya JD, Morello A, Repetto Y, Rodríguez A, Puebla P, Caballero E, Medarde M, Núñez-Vergara LJ, Squella JA, Ortiz ME, Fuentealba J, San Feliciano A. Trypanosoma cruzi: inhibition of parasite growth and respiration by oxazolo(thiazolo)pyridine derivatives and its relationship to redox potential and lipophilicity. Exp Parasitol 2001; 99:1-6. [PMID: 11708828 DOI: 10.1006/expr.2001.4638] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chagas' disease constitutes a therapeutic challenge because presently available drugs have wide toxicity to the host and are generally ineffective in the chronic stages of the disease. A series of oxazolo(thiazolo)pyridene derivatives were studied on Trypanosoma cruzi epimastigote growth and oxygen consumption and their electrochemical (redox) potentials and lipophilicity. The derivatives produced different degrees of parasite growth and respiration inhibition on CL Brener, LQ, and Tulahuen strains of T. cruzi epimastigotes. Respiratory chain inhibition appears to be a determinant of the trypanosomicidal activity of these compounds, since a significant correlation between respiration and culture growth inhibition was found. A similar correlation was found, within the different structural subfamilies, between toxic effects and the ability of the compounds to be oxidized in aqueous media. The inhibition of respiration and of parasite growth in culture increases with the lipophilicity of the substituents on the oxazolopyridine nucleus. No difference in the action of these derivatives was found among the different parasite strains. It is concluded that these compounds may have a potential usefulness in the treatment of Chagas' disease.
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Affiliation(s)
- J D Maya
- Program of Clinical and Molecular Pharmacology, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago 7, Chile
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27
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Morello A, Maresi E, Villari L. Late sequelae of pontine lesions by acute uncal herniation. J Neurosurg Sci 2001; 45:47-52. [PMID: 11466508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
The authors report the late macro- and microscopic aspects of the brainstem lesions found in two patients who survived an acute uncal herniation, respectively, 176 and 62 days. They also describe the evolution of the clinical picture characterized by the complete disappearance of initially present neurological signs but by a persistent comatose state.
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Affiliation(s)
- A Morello
- Neurosurgical Department, University of Palermo, Palermo, Italy
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28
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Aguillón JC, Hermosilla T, Molina MC, Morello A, Repetto Y, Orn A, Ferreira A. Trypanosoma cruzi: H2 complex and genetic background influence on the humoral immune response against epimastigotes. Int J Parasitol 2000; 30:981-4. [PMID: 10980286 DOI: 10.1016/s0020-7519(00)00078-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Using A.SW, A.CA, B10.S and B10.M congenic mouse strains, we measured the IgG specific humoral immune responses against sonicated and live Trypanosoma cruzi epimastigotes. Genes located in the A background (A.SW and A.CA strains) mediate higher IgG responses against the parasite antigenic complexes than those located in the B background (strains B10.S and B10.M), regardless of the H2 haplotypes. Thus, non H2 genetic elements seem to be more important in determining differences in the total IgG immune response against T. cruzi. Whether a detectable H2 effect, in favor of the H2(s) haplotype, occurred in the A or B background, was contingent on the immunisation protocol used. Thus, the H2(s) haplotype mediates a higher IgG response in the A background, if immunised with live epimastigotes, and in the B background against sonicated epimastigotes. Most likely this represents a complex sequence of events, controlled by non-MHC genes, involving antigen handling and processing and depending on the physical form of antigen delivery.
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Affiliation(s)
- J C Aguillón
- Programa de Inmunología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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29
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Maya JD, Morello A, Repetto Y, Tellez R, Rodriguez A, Zelada U, Puebla P, Caballero E, Medarde M, Núñez-Vergara LJ, Squella JA, Bontá M, Bollo S, San Feliciano A. Effects of 3-chloro-phenyl-1,4-dihydropyridine derivatives on Trypanosome cruzi epimastigotes. Comp Biochem Physiol C Toxicol Pharmacol 2000; 125:103-9. [PMID: 11790334 DOI: 10.1016/s0742-8413(99)00096-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A series of 3-chloro-phenyl-1,4-dihydropyridine derivatives produced different degrees of inhibition of parasite growth and respiration on clone Brener, LQ and Tulahuen strains of Trypanosome cruzi epimastigotes. Respiratory chain inhibition appears to be a posible determinant of the trypanosomicidal activity of this compounds. No difference in the action of these derivatives was found among the different parasite strains. For comparative purposes, the inhibitory effects of felodipine and nicardipine are also reported. A good correlation between toxic effects and the easiness of oxidation of the dihydripyridine ring was found. The presence of a fused ring on the dihydropyridine moiety significantly diminished the inhibitory effects.
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Affiliation(s)
- J D Maya
- Program of Clinical and Molecular Pharmacology, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, PO Box 70086, Santiago, Chile
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Morello A, Lentini G, Gambino G, Randisi MG. Stretching (?) of the spinal cord as a cause of paraplegia in a patient with Cushing's syndrome. J Neurosurg Sci 1999; 43:201-3. [PMID: 10817388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Paraplegia with a total anesthesia level was found in a patient who had Cushing's syndrome. There was marked osteoporosis of the spine and a moderate wedge shaped compression fracture of the T4 vertebral body but no stenosis of the canal could be observed. On the grounds of the CT findings stretching of the spinal cord caused by the rapidly evolving kyphosis of the thoracic tract has been thought to be the responsible factor of the clinical deficits.
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Affiliation(s)
- A Morello
- Institute of Neurosurgery, University of Palermo
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31
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Morello A, Pappalardo S, Di Leonardo S, De Crescenzo L, Virga G. Efficacy of corticosteroid therapy on cerebral gummas: risks and implications. J Neurosurg Sci 1999; 43:53-7. [PMID: 10494666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Complete resolution of a cerebral gumma can take place after massive corticosteroid treatment. Such a result in patients not known as syphilitic can be misleading and hamper the identification of the true nature of the lesion.
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Affiliation(s)
- A Morello
- Department of Neurosurgery, University of Palermo, Italy
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Rivas P, Cassels BK, Morello A, Repetto Y. Effects of some beta-carboline alkaloids on intact Trypanosoma cruzi epimastigotes. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 1999; 122:27-31. [PMID: 10190025 DOI: 10.1016/s0742-8413(98)10069-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Several beta-carboline (9H-pyrido-[3,4-b]-indole) alkaloids were evaluated for in vitro trypanosomicidal activity against Trypanosoma cruzi epimastigotes belonging to two different strains (Tulahuén and LQ) showing different sensitivity to nifurtimox. Important differences were observed in the susceptibility of the parasites to these natural substances, with the relatively nifurtimox-resistant LQ strain showing greater sensitivity to the beta-carbolines. Respiratory chain inhibition appears to be a possible determinant of the trypanosomicidal activity of these compounds.
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Affiliation(s)
- P Rivas
- Department of Chemistry, Faculty of Sciences, University of Chile, Santiago.
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Arana FE, Pérez-Victoria JM, Repetto Y, Morello A, Castanys S, Gamarro F. Involvement of thiol metabolism in resistance to glucantime in Leishmania tropica. Biochem Pharmacol 1998; 56:1201-8. [PMID: 9802332 DOI: 10.1016/s0006-2952(98)00129-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Clinical resistance to pentavalent antimonials, in the form of pentostam (sodium stibogluconate) or glucantime (N-methylglucamine antimoniate), has long been recognized as a problem in Leishmaniasis. However, the mechanisms of resistance are unclear. We selected in vitro a Leishmania tropica line resistant to 1.2 mg/mL of Sb(V) of glucantime (GLU-R10). The cell line has a stable phenotype for at least 6 months and a resistance index of 1400-fold. The resistant line has no cross-resistance to pentostam or to SbCl3 and SbCl5. The resistance to glucantime was reverted by buthionine sulfoximine (BSO) and chlorambucil (CLB); however, thiol analyses by HPLC of wild-type and GLU-R10 cell lines, in the presence or absence of the drug, showed no differences between these two cell lines. The resistant line had a DNA amplification shown as a circular extrachromosomal element (G-circle) of approximately 22 kb. However, the specific probes for gamma-glutamyl cysteine synthetase, ornithine decarboxylase and trypanothione reductase did not recognize the G-circle amplified in the GLU-R10. The G-circle did not arise from the H region and was not related with P-glycoprotein Pgp-MDR- or Pgp-MRP-like genes. Northern blot analysis of the G-circle showed that a single transcript of approximately 6 kb was overexpressed in the resistant line. Molecular characterization of the G-circle would lead to the determination of the gene(s) involved in resistance to glucantime in Leishmania.
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Affiliation(s)
- F E Arana
- Instituto de Parasitología y Biomedicina López-Neyra, Consejo Superior de Investigaciones Científicas, Granada, Spain
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Núñez-Vergara LJ, Squella JA, Bollo-Dragnic S, Morello A, Repetto Y, Aldunate J, Letelier ME. Nitro aryl 1,4-dihydropyridine derivatives: effects on Trypanosoma cruzi. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 1997; 118:105-11. [PMID: 9366041 DOI: 10.1016/s0742-8413(97)00078-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A series of nitro aryl 1,4-dihydropyridine derivatives produced inhibition of both cell growth and oxygen consumption on Tulahuen and LQ strains, and clone Dm 28c of epimastigotes of Trypanosoma cruzi. Nicardipine was found to be the most potent derivative in both growth cell (I50 = 70 microM) and oxygen uptake (I50 = 26 microM in intact parasites, I50 = 325 microM in situ mitochondria). A correlation between the inhibitory effects on the growth cell and the apparent first order kinetic for the uptake of the 1,4-dihypyridine derivatives by T. cruzi epimastigotes was found. Thus, nicardipine, the most potent derivative, exhibited the highest apparent rate constant, ku, (0.043 min-1). On the other hand, no susceptibility differences by strains and clone Dm 28c to the action of these drugs were found.
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Affiliation(s)
- L J Núñez-Vergara
- Laboratory of Bioelectrochemistry, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago, Chile
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Núñez-Vergara LJ, Squella J, Aldunate J, Letelier M, Bollo S, Repetto Y, Morello A, Spencer P. Nitro radical anion formation from nifurtimox. Part 1: Biological evidences in Trypanosoma cruzi. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0302-4598(96)05188-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Maya JD, Repetto Y, Agosín M, Ojeda JM, Tellez R, Gaule C, Morello A. Effects of nifurtimox and benznidazole upon glutathione and trypanothione content in epimastigote, trypomastigote and amastigote forms of Trypanosoma cruzi. Mol Biochem Parasitol 1997; 86:101-6. [PMID: 9178272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- J D Maya
- Departmento de Farmacologia, Instituto de Ciencias de la Salud (CES), Medellin, Colombia
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37
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Giuffrè M, Amato GM, Manfrè L, Morello A. [Discitis in childhood: integrated neuroradiological imaging in diagnosis and follow-up study of one case]. Minerva Pediatr 1997; 49:101-7. [PMID: 9198729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Discitis is an inflammatory disease of the intervertebral disc which has usually a benign evolution in childhood. It often recognizes an infectious etiology. Still discussed however is the possibility of a primitive discal involvement (not secondary to a vertebral inflammation) or of a non infectious etiology and the subsequent more correct diagnostic-therapeutic procedures. We report a case of a girl with discitis diagnosed early and treated with antibiotics and orthopedic corset, whose follow-up shows a benign evolution. We underline the importance of modern neuroradiological imaging: in particular, MR plays a major role in the inflammatory diseases of the column, both in diagnosis and in follow-up. MR scans of the involved disc allow frequent controls without radiogenic risks and with a good resolution because of the multiplanarity typical of the method.
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Affiliation(s)
- M Giuffrè
- Istituto di Pediatria, Università degli Studi, Palermo
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38
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Idígora A, Morello A, Maristany M, Larrosa F, Romero E, Traserra J. [Phyolaryngocele: a case report and review of literature]. Acta Otorrinolaringol Esp 1997; 48:73-7. [PMID: 9131933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A case of pyolaryngocele presented as a lateral cervical mass that produced acute dyspnea requiring tracheotomy. The diagnosis was by direct laryngoscopy, which revealed outflow of purulent material with pressure on the tumor, and was confirmed by CT. Broad-spectrum antibiotic treatment was given and the pyolaryngocele was excised by lateral extramucosal tyrotomy. The literature on laryngocele and pyolaryngocele was reviewed.
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Affiliation(s)
- A Idígora
- Servicio ORL, Hospital Clínic i Provincial de Barcelona
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39
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Pérez Villa J, Pérez Villa FC, Morello A, Betriu A, Traserra J. [Topographic diagnosis of hearing loss in patients with ischemic heart disease. Use of high-rate brain stem evoked response audiometry]. Acta Otorrinolaringol Esp 1996; 47:441-7. [PMID: 9044583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Hearing loss in patients with ischemic heart disease traditionally has been attributed to atheromatous cerebral vascular disease. In this study, the site of the auditory lesion was sought in patients with ischemic heart disease and perceptive hearing loss. Standard brainstem evoked response audiometry (BSER) with increased stimulation rate (ISR) were performed. Sixty-seven patients admitted for coronary artery disease were examined. Fifty-seven recordings were complete and evaluable. All the cases of hearing loss were endocochlear. In 4 patients. BSER and ISR detected subclinical retrocochlear lesions that were compatible with ischemic disease. The results suggest that selective early cochlear ischemia can occur in young persons with heart disease. The sensitivity of BSER with ISR for detecting ischemic brainstem lesions was confirmed.
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Affiliation(s)
- J Pérez Villa
- Servicio de ORL, Cátedra de ORL, de la Universidad de Barcelona
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40
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Biurrun O, Morello A, Traserra J. [Surgical multiple level reconstruction of the upper airways for treatment of obstructive sleep apnea. Two clinical cases]. Acta Otorrinolaringol Esp 1996; 47:479-83. [PMID: 9044591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Techniques for surgical correction of the soft palate are used commonly to treat obstructive sleep apnea syndrome (OSAS), but a satisfactory cure cannot be ensured because such techniques usually involve localized correction of the upper airways (UA) whereas UA collapse during sleep involves the entire length. The development of correction techniques for the entire extension of the UA may help to solve this problem. We report the first two cases of multilevel UA surgical reconstruction in OSAS performed in Spain. The excellent results obtained favor routine use of this type of surgery once it has been validated in clinical practice.
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Affiliation(s)
- O Biurrun
- Servicio de ORL, Hospital Clínico de Barcelona
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41
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Repetto Y, Opazo E, Maya JD, Agosin M, Morello A. Glutathione and trypanothione in several strains of Trypanosoma cruzi: effect of drugs. Comp Biochem Physiol B Biochem Mol Biol 1996; 115:281-5. [PMID: 8939007 DOI: 10.1016/0305-0491(96)00112-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Glutathione (GSH), trypanothione (T(SH)2) and glutathionyl spermidine (GSH-SP) concentrations were determined in the Tulahuén and LQ strains and the DM 28c clone of Trypanosoma cruzi. The concentrations of GSH, T(SH)2 and GSH-SP, expressed as nmol of GSH per g of parasite fresh weight, were 60.1, 397.8 and 103.9, respectively, for the Tulahuén strain. For the DM 28c clone, the values were 113.9, 677.9 and 164.1, respectively, and for the LQ strain they were 199.1, 1100.5 and 55.3, respectively. When the parasites were treated with 10 microM nifurtimox or 50 microM benznidazole for 2 h, the concentrations of all three reduced thiols decreased strongly. The total amount of T(SH)2 decreased by more than 50%. Treatment of the parasites with 5 mM buthionine sulfoximine, an inhibitor of GSH synthesis, for 6 h diminished the concentrations of the reduced thiols by between 27% and 53% with respect to the controls. Cyclohexylamine, an inhibitor of spermidine synthesis, decreased the concentrations of T(SH)2 and GSH-SP but not that of GSH. It is possible to conclude from this study that trypanothione is the most important thiol involved in the detoxication of nifurtimox and benznidazole in T. cruzi and that electrophilic reduced metabolites of both drugs are most probably conjugated with GSH, T(SH)2 and GSH-SP, thus decreasing their concentrations. GSH biosynthesis is an important drug target.
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Affiliation(s)
- Y Repetto
- Department of Biochemistry, Faculty of Medicine, University of Chile, Santiago, Chile
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42
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Montserrat JM, Ballester E, Olivi H, Reolid A, Lloberes P, Morello A, Rodriguez-Roisin R. Time-course of stepwise CPAP titration. Behavior of respiratory and neurological variables. Am J Respir Crit Care Med 1995; 152:1854-9. [PMID: 8520746 DOI: 10.1164/ajrccm.152.6.8520746] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Because successful medical treatment of obstructive sleep apnea/hypopnea syndrome (SAHS) depends on adequate CPAP treatment, we have analyzed in nine SAHS patients the behavior of respiratory and neurological parameters during a stepwise, polysomnography-controlled CPAP titration to achieve an optimal CPAP. Particularly, we have focused on which simple variable could predict the optimal CPAP pressure and could better define a distinctive optimal-suboptimal pattern. Main parameters analyzed through the CPAP titration procedure were respiratory events (apnea, hypopnea), the contour of inspiratory flow, the pleural pressure behavior, the thoraco-abdominal motion, oximetry, arousals, and sleep stage. During the CPAP titration we observed: (1) a rounded shape in the inspiratory flow contour was associated with the lowest esophageal pressure; (2) during stepwise increases in CPAP, almost all apnea events changed to hypopnea periods, followed by prolonged periods of limited inspiratory flow with still high esophageal pressure but without arousals (probably suboptimal CPAP); and (3) as CPAP reached suboptimal levels, sleep stage moved to deeper stages without arousals. We conclude that if during CPAP titration the end point is the disappearance of arousals, most patients with SAHS will still exhibit periods of high intrathoracic pressures with limited inspiratory flow. Alternatively, if the end point to be reached is the lowest esophageal pressure, higher CPAP levels will be needed. The contour of inspiratory flow appears as the simplest variable that best correlates with lowest esophageal pressure during CPAP titration.
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Affiliation(s)
- J M Montserrat
- Servei de Pneumologia i Allèrgia Respiratòria, Universitat de Barcelona, Spain
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43
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Morello A, Pavani M, Garbarino JA, Chamy MC, Frey C, Mancilla J, Guerrero A, Repetto Y, Ferreira J. Effects and mode of action of 1,4-naphthoquinones isolated from Calceolaria sessilis on tumoral cells and Trypanosoma parasites. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 1995; 112:119-28. [PMID: 8788584 DOI: 10.1016/0742-8413(95)02003-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The naphthoquinones 2-hydroxy-3-(1,1-dimethylallyl)-1,4-naphthoquinone (CS-1), (-)-2,3,3-trimethyl-2-3-dihydronaphtho[2,3-b]furan-4,9-quinone (CS-3), and 2-acetoxy-3-(1,1-dimethylallyl)-1,4-naphthoquinone (CS-5) isolated from Calceolaria sessilis were tested against Trypanosoma cruzi epimastigotes, the TA3 tumor cell line and the methotrexate-resistant subline TA3-MTX-R. Naphthoquinone CS-3 was the most active; the 50% culture growth inhibition (I50) on T. cruzi (Tulahuén and LQ strain and DM28c clone) was at concentrations ranging from 2.1 to 5.2 mumolar. Also CS-3 inhibited TA3 and TA3-MTX-R culture growth with an I50 of 2.1 and 3.8 mumolar, respectively. Naphthoquinone CS-3 inhibited the respiration of the tumor cells by interfering with the electron transport at some point between NADH and ubiquinone. The respiration of T. cruzi was not inhibited by naphthoquinone CS-3. Naphthoquinone CS-3 produced a temporary increase of oxygen consumption in T. cruzi and tumor cells, suggesting the generation and participation of free radicals.
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Affiliation(s)
- A Morello
- Department of Biochemistry, University of Chile Santiago
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44
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Núñez-Vergara LJ, Aldunate J, Letelier M, Bollo S, Repetto Y, Morello A, Spencer P, Squella J. Nitro radical anion formation from nifurtimox II: electrochemical evidence. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/0302-4598(95)05023-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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45
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Aguillon JC, Bustos C, Vallejos P, Hermosilla T, Morello A, Repetto Y, Hellman U, Orn A, Ferreira A. Purification and preliminary sequencing of Tc-45, an immunodominant Trypanosoma cruzi antigen: absence of homology with cruzipain, cruzain, and a 46-kilodalton protein. Am J Trop Med Hyg 1995; 53:211-5. [PMID: 7677227 DOI: 10.4269/ajtmh.1995.53.211] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
In spite of being separated by more than 20 million years of evolution, the murine and human immune systems share extensive similarities. Thus, experimental results obtained with the murine model may have predictive value for human Chagas' disease. Challenge of the H-2 congenic mouse stains A.SW (H-2s) and A.CA (H-2f) with Trypanosoma cruzi yields different results. The A.CA animals die approximately 12 days postinfection, while A.SW mice survive indefinitely. A 45-kD protein (Tc45), an antigen differentially recognized by the A.SW strain, is present in cultured epimastigotes and blood trypomastigotes. We describe here its purification from epimastigotes. The presence of Tc45 was monitored and a single band was detected. Since the molecular weights of Tc45, cruzipain, cruzain, and a 46-kD parasite polypeptide are similar, it was important to determine if these molecules are related. A complete lack of homology was observed when the sequence of cruzain, cruzipain, and the 46-kD polypeptide were compared with the preliminary sequence of Tc45.
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Affiliation(s)
- J C Aguillon
- Departamento de Medicina Preventiva Animal, Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago
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46
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Biurrun O, Morello A, Roca J, Barberá JA, Rodríguez-Roisín R, Traserra J. [Adaptable and portable cephalometric devices: a new method in obtaining cephalometrics]. Acta Otorrinolaringol Esp 1995; 46:293-7. [PMID: 7546855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cephalometric radiographic explorations are widely recommended in the diagnosis of the obstructive sleep apnea syndrome (OSAS). In order to improve their diagnostic value, its practice in the upright and supine position has been proposed. A rigorous practice of cephalometric requires the employment of cephalometric devices in order to assure a correct positioning of the head and provide reliable X-ray pictures, comparable within reasonable accuracy over a period of time. The commercialized cephalostats are often expensive due to the structural conditions needed for their development and usually they not allow the simultaneous practice of upright and supine cephalometric. In this paper we describe a cephalometric adaptable device, developed by our research group, that may solve such problems.
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Affiliation(s)
- O Biurrun
- Servicio de ORL, Hospital Clínico de Barcelona
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47
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Biurrun O, Mulet J, Morello A, Guirado C, Ordi J, Molinero M, Traserra J. [Carotid paraganglioma: a case report]. Acta Otorrinolaringol Esp 1995; 46:327-30. [PMID: 7546863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Carotid paraganglioma are tumors arising from chemoreceptor paraganglioma cells. These cells have proved to have an embryologic origin from the neural crests. Due to their low incidence these tumors are not an habitually found in daily practices. We present a case of carotid body paraganglioma diagnosed by clinical exploration, CT scan, magnetic resonance imaging and magnetic resonance angiography which was successfully treated by surgery. The diagnostic and therapeutic difficulties present in these tumors are discussed.
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Affiliation(s)
- O Biurrun
- Unidad de ORL, Hospital General de Vic, Barcelona
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48
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Pérez Villa J, Pérez Villa FC, Morello A, Betriu A, Traserra J. [Neurosensory hearing loss associated with ischemic heart disease. Features and prognostic values]. Acta Otorrinolaringol Esp 1995; 46:165-70. [PMID: 7619548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The aim of this study was to verify the supposed pathological hearing loss in those patients with ischemic heart disease, as well as to determine its features and possible clinical usefulness. Two groups were made: group A (n = 65), patients admitted for acute episode of ischemic heart disease, group B (n = 60), patients without cardiac or auditive disorders. Auditive assessment included standard PTA and Bera. Cardiologic evaluation was made through cardiac catheterism with coronariography. Results confirm the existence of a clinical association between "perceptive hearing loss" and "ischemic heart disease", independently of the age, with a characteristic pattern of hearing loss, and also show the existence of a high risk subgroup within the population with coronary risk.
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Affiliation(s)
- J Pérez Villa
- Hospital Clínico Provincial de Barcelona Cátedra de ORL de la Universidad de Barcelona
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49
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Morello A, Lipchenca I, Cassels BK, Speisky H, Aldunate J, Repetto Y. Trypanocidal effect of boldine and related alkaloids upon several strains of Trypanosoma cruzi. Comp Biochem Physiol Pharmacol Toxicol Endocrinol 1994; 107:367-71. [PMID: 8061943 DOI: 10.1016/1367-8280(94)90063-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The alkaloids boldine, glaucine, predicentrine, apomorphine, coclaurine, norarmepavine and codeine were tested against the epimastigotes of the Tulahuén and LQ strains and the DM 28c clone of Trypanosoma cruzi. The micromolar concentration to inhibit 50% of the culture growth (Tulahuén strain) for apomorphine, glaucine, predicentrine, boldine, norarmepavine, coclaurine and codeine were 29, 90, 85, 110, 310, 580 and > 1000 respectively. Similar values were obtained with the LQ strain and the DM 28c clone. The most active compounds in inhibiting culture growth also inhibited cell respiration, suggesting that these drugs may act by blocking mitochondrial electron transport. The trypanocidal effects of these alkaloids appear to be correlated with their antioxidative activities.
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Affiliation(s)
- A Morello
- Department of Biochemistry, Faculty of Medicine, University of Chile, Santiago
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50
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Abstract
1. Hydroquinones inhibited the culture growth of Trypanosoma cruzi epimastigotes at concentrations lower than 1 mM. 2. Hydroquinones inhibited the oxygen consumption on the intact Trypanosoma cruzi cells. I50 values for hydroquinone, terbutylhydroquinone and 2,5-di-t-butylhydroquinone were 24.87 mM, 0.88 mM and 0.26 mM, respectively. t-Butylhydroquinone and 2,5-di-t-butylhydroquinone had a Michaelian type kinetic inhibition; hydroquinone also showed a Michaelian type kinetic inhibition at low concentrations but at higher concentrations it showed a positive cooperativity. 3. These hydroquinones changed the NAD(P) redox-state to a more reduced state and that of cytochrome b to a more oxidized state. The magnitude of the redox-state change was dependent of the hydrophobicity of the derivates. 4. These results suggest that the growth and oxygen uptake inhibition by the hydroquinones is due to a blockage of the mitochondrial electron transport chain before cytochrome b.
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Affiliation(s)
- J Aldunate
- Department of Biochemistry, Faculty of Medicine, University of Chile, Santiago
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